For instance, are they developing something innovative and unique to their brand besides the design? My guess is yes because I always hear how they are working on the next big thing, like 20nm chips, and racing to get there first. But then I read that they order pieces from different manufacturers and assemble them so I'm confused.
If you are evaluating companies for the purpose of purchasing miners, there's only one property of their equipment you should be interested in: previous shipping track record.
28nm or 20nm, Gh/s, W/Gh, etc, all are unimportant. Just follow the reports if that company delivers on time or not, you can be promised most advanced equipment in the universe, but it's not worth as much as inferior design delivered on time.